Among the speakers addressing the large crowd on Saturday was Helen Davies, founder of the Rainbow Rehoming Centre in Co Londonderry.

She said she received regular complaints from members of the public who had unwittingly bought puppies from such farms.

"Each caller had responded to an advertisement in a newspaper or online, and had agreed to meet a breeder, usually in a car park, because the breeder insisted this would save the caller a long and complicated journey to his 'home'," said Helen.

"After choosing a puppy from a van-load of caged puppies, the owner took the puppy home, only to find soon afterwards that the animal was unwell."

She added: "It appals me that not only is this vile practice still going on, but it has been allowed to flourish, due to the failure of councils."